Get the Serial Number of a X509 Certificate

X509CertificateUtils.java

package com.neptuneli.utils;

import java.math.BigInteger;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

public class X509CertificateUtils {

  public String getCertSerialNo(final String certPath) {

    FileInputStream fileInputStream = null;
    String serialNo = null;

    try {
      fileInputStream = new FileInputStream(certPath);

      final BouncyCastleProvider provider = new BouncyCastleProvider();
      final CertificateFactory certificateFactory = CertificateFactory.getInstance("X509", provider);
      final X509Certificate certificate = (X509Certificate) certificateFactory.generateCertificate(fileInputStream);
      final BigInteger serialNumber = certificate.getSerialNumber();

      serialNo = serialNumber.toString();

    } catch (final FileNotFoundException e1) {
      e1.printStackTrace();
      System.err.println("Cannot find the X509 certificate");

    } catch (final Exception e2) {
      e2.printStackTrace();
      System.err.println("Cannot parse the serial number");

    } finally {
      if (fileInputStream != null) {
          try {
            fileInputStream.close();

          } catch (final IOException e3) {
            e3.printStackTrace();
            System.err.println("Cannot close the certificate input stream");
          }
      }
    }
    
    return serialNo;
  }
}